Hi,
I made my first shots with a speed graphic. Unfortunately I discoverd 2 vertical lines on my processed sheet. They are at 1cm from each border. The sheet was not correctly inserted. The emulsion was at the wrong side. Would that be the reason? It was a Ilford delta 100 sheet. Some say it the lens board. Other say it's the holder? Couls somebody help me?
http://photo.net/photodb/photo?photo_id=11165316

You've got some irregular dense area near the light trap as well (right side). Without seeing your set up with the film holder and dev tanks, it's hard to say, but I have to wonder if it isn't a processing error.

It can't be the lens board._________________"In order to invent, you need a good imagination and a lot of junk" Thomas Edison

hey Pierre
HOW BLACK is the inside of your camera some times if
you have some thing shinney on the inside you can get a
Ghost Reflection ! get out some flat black pant & go to work
on any thing shinney!
banjo

The lines seem too consistent to be reflections but I cannot rule that out either. In a darkroom with the light off, the focus panel removed, bellows fully extended and the or one of the lens/shutter used in the questionable photos attached put a 2 AA cell mini mag flash light or similar inside the bellows and look for light coming from around the shutter and or lens board. Next remove the lens board and reinstall the focus panel, install a film holder, retract the bellows only enough to easily shine the flash light around the edges of the back and film holder and check for any hint of light coming from around the back or film holder. Weak light leaks will look like dim yellow dots or streaks, strong ones will look white.

I have had pin holes in bellows put secondary exposures on the film. Light leaks do not always cause flair like streaks._________________The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.

I think I found the reason of those vertical lines on the sheets. I used another lens and the lines didn't appear. They might have been some sort of reflection of the camera's rail through the lens I used.